In motors and generators employing electromagnetic rotors which are connected by commutator brushes to a power source or load, the brushes, usually carbon, may wear or fracture resulting in poor performance or in motor or generator failure. Particularly in the case of d-c motors used in variable speed drive of critical systems elements, the consequential damages of inadequate motor performance can be significant and, in fact, cause commutator destruction. By way of one example, in the art of weaving it is well known to provide a weft or filling yarn storage feeder device, referred to herein simply as a "yarn feeder", which operates to store yarn for use by a loom, normally a shuttleless loom. The device includes a yarn collecting drum on which weft yarn from a supply source is wound temporarily and then removed under controlled, uniform tension for delivery to the loom. Such devices eliminate the wide variations in yarn tension which occur when yarn is delivered from a supply source such as a cone or package, and permits the yarn to be fed to the loom under substantially constant tension. This art is exemplified by U.S. Pat. No. 3,776,480 to John B. Lawson granted Dec. 4, 1973 and U.S. Pat. No. 3,853,153 granted Dec. 10, 1974 to A. H. Van Duyhoven et al. Typically, such yarn feeders may have either a rotary drum upon which the yarn is wound as the drum is driven by a suitable motive source such as an electric motor or the feeders may incorporate a stationary drum with an orbiting flyer driven by, say, an electric motor and engaging the welft yarn to apply it to the surface of the stationary drum. If the yarn feeder is not operated at proper start or stop time or at proper speed the critical yarn feed mechanism is likely to cause shutdown of the machinery because of jamming or improper yarn feed.
Motor operation monitors of the prior art were not practically operable in such textile systems because in essence the prediction of erratic operation or motor failure was not feasible. There have been brush wear indicators which switched on alarm circuits when the brush has worn a predetermined amount. These characteristically require physical modification of the brush holder or the brush itself to add a sensing switch or contact. However, these prior art indicators could not indicate fractured brushes, mispositioned brushes or other brush-commutator indications of erratic motor operation, exhibition of which is desirable to prevent down time in the textile machine and the like.
Examples of these brush wear detectors and monitors are found in the following U.S. Patents, U.S. Pat. No. 4,121,207 issued Oct. 17, 1978 to F. L. Jones; U.S. Pat. No. 4,316,186 issued Feb. 16, 1982 to J. A. Purdy et al; U.S. Pat. No. 4,024,525 issued May 17, 1977 to K. A. Baumgartner et al; and U.S. Pat. No. 3,523,288 issued Aug. 4, 1970 H. A. Thompson.
Other objects, features and advantages will be found throughout the description, claims and drawings.
It is therefore an object of this invention to produce improved systems for detecting and monitoring erratic operation of brush and commutator connected electromagnetic rotating machinery such as d-c motors and generators to predict and resolve failure before consequential damages from the failure result.